Gas exchange system for extended in situ benthic chamber flux measurements under controlled oxygen conditions: First application - Sea bed methane emission measurements at Captain Arutyunov mud volcano

Mass transfer rates of many gases, nutrients, and trace metals across the sediment water interface are dependent on environmental oxygen conditions. In this article, a novel gas exchange system for extended in situ flux and respiration measurements in benthic chambers under defined oxygen conditions is described. Integrated within a GEOMAR modular lander, the gas exchange system was used to perform in situ measurements of the total oxygen uptake and sea bed methane emission rates under constant oxygen conditions at Captain Arutyunov mud volcano (Gulf of Cadiz) in a water depth of 1320 m. During two separate lander deployments, the oxygen concentration within the benthic chambers was kept constant for 37 and 47 h, respectively. Under these conditions total oxygen uptake rate remained constant at 4.4 and 13.2 mmol m�2 d�1. Seabed methane emission was low, in the range 0 to 0.2 mmol m�2 d�1. The system is suited for prolonged (days) in situ flux determinations under natural background oxygen conditions and offers a wide range of experimental application

Entwurf eines Drahtlos-Sensornetzwerkes unter Nutzung von "Energy-Harvesting" Komponenten

Ziel der Diplomarbeit ist der Entwurf eines Drahtlos-Messsystems zur Messwerterfassung von einem oder mehreren verteilten Messpunkten, „sog. RFNodes“, durch Nahbereich Funk und Übertragung an ein Steuersystem via einem „sog. RF-Gateway“. Die „RF-Nodes“ verfügen zusätzlich über eine autarke Energieversorgung. Es werden die Möglichkeiten zum Einsatz von geeigneten „Energy-Harvesting“ Systemen aufgezeigt. Nach Durchführung einer „Stand der Technik“- Recherche wird ein elektrisches Konzept zur Realisierung des Drahtlos-Netzwerkes sowie der Energy-Harvesting Komponente erstellt. Dieses System wird im Laborumfeld aufgebaut. Die Basisfunktion wird anhand dieses Prototypen verifiziert und optimiert

Recurrent abscess after primary successful endo-sponge treatment of anastomotic leakage following rectal surgery

AIM: To assess long-term efficacy of initially successful endo-sponge assisted therapy

Impact of SSTR PET on Inter-Observer Variability of Target Delineation of Meningioma and the Possibility of Using Threshold-Based Segmentations in Radiation Oncology

Aim: The aim of this study was to assess the effects of including somatostatin receptor agonist (SSTR) PET imaging in meningioma radiotherapy planning by means of changes in inter-observer variability (IOV). Further, the possibility of using threshold-based delineation approaches for semiautomatic tumor volume definition was assessed. Patients and Methods: Sixteen patients with meningioma undergoing fractionated radiotherapy were delineated by five radiation oncologists. IOV was calculated by comparing each delineation to a consensus delineation, based on the simultaneous truth and performance level estimation (STAPLE) algorithm. The consensus delineation was used to adapt a threshold-based delineation, based on a maximization of the mean Dice coefficient. To test the threshold-based approach, seven patients with SSTR-positive meningioma were additionally evaluated as a validation group. Results: The average Dice coefficients for delineations based on MRI alone was 0.84 ± 0.12. For delineation based on MRI + PET, a significantly higher dice coefficient of 0.87 ± 0.08 was found (p < 0.001). The Hausdorff distance decreased from 10.96 ± 11.98 mm to 8.83 ± 12.21 mm (p < 0.001) when adding PET for the lesion delineation. The best threshold value for a threshold-based delineation was found to be 14.0% of the SUVmax, with an average Dice coefficient of 0.50 ± 0.19 compared to the consensus delineation. In the validation cohort, a Dice coefficient of 0.56 ± 0.29 and a Hausdorff coefficient of 27.15 ± 21.54 mm were found for the threshold-based approach. Conclusions: SSTR-PET added to standard imaging with CT and MRI reduces the IOV in radiotherapy planning for patients with meningioma. When using a threshold-based approach for PET-based delineation of meningioma, a relatively low threshold of 14.0% of the SUVmax was found to provide the best agreement with a consensus delineation